Louisiana National Guard Sgt. 1st class Anthony Stuttle, right, instructs members of the 256th Charlie Co. to secure their vehicles before moving into the Ernest N. Morial Convention Center in New Orleans.

NEW ORLEANS  Gulf Coast residents began fleeing low-lying areas Saturday as Gustav, packing 120 mph winds, swelled to a Category 3 hurricane on a path to slam into the U.S. coast somewhere between Texas and the Florida Panhandle around midnight Monday.

The U.S. National Hurricane Center in Miami called the storm "dangerous" and warned that it could grow into a Category 4 hurricane as it draws energy from the warm waters of the Gulf of Mexico over the weekend.

At 11 a.m. ET, the center of Gustav was about 185 miles east of the western tip of Cuba. The storm had maximum sustained winds of 125 mph, just 6 mph shy of the Category 4 threshold. The eye was to pass over western Cuba later Saturday and strengthening is forecast after it reaches the Gulf of Mexico.

New Orleans, which was devastated by Hurricane Katrina almost exactly three years ago, ordered all non-residents and hotel guests to leave the area and was prepared to issue a mandatory evacuation order for all residents. Nearby St. Bernard Parish issued a mandatory evacuation order effective 5 p.m.ET.

Mayor Ray Nagin's spokeswoman said buses and trains would begin Saturday taking the city's estimated 30,000 residents who are disabled, elderly or need help leaving the area to shelters in central and northern Louisiana, as well as out of the state.

Louis Armstrong International Airport announced that it would shut down all flights at 7 p.m. ET on Sunday.

"We look ahead to a better day, as we also prepare ourselves for another threat," Nagin said at a ceremony at a mausoleum to bury the seven remaining unclaimed Katrina victims.

The entire Louisiana National Guard, over 7,000 members, was activated on Friday. Over 1,500 were sent to New Orleans to assist with evacuations and prevent looting. Gov. Bobby Jindal sought to reassure New Orleans residents, who recall rampant looting during Katrina, that the guard and New Orleans police would fight any recurrence.

"We don't want folks worrying about their property. It is time for people to be worried about their personal safety," Jindal said.

Mississippi Governor Haley Barbour also urged Katrina victims still living in FEMA trailers and mobile homes, as well as residents in flood zones, to begin evacuating this weekend. Notices will be going out Saturday to FEMA trailer residents, he said in a news release.

The Mississippi Army National Guard was prepared to go door-to-door on Saturday to notify people living in low-lying areas, flood hazard zones, FEMA travel trailers and mobile homes and Mississippi Cottages to seek alternative shelter because of the threat of severe tropical weather.

"There is no question we are taking this storm seriously," Barbour said, "but there is no need to panic."

In New Orleans, reverse traffic flow was expected to begin at 6 p.m. Officials plan to announce a curfew that will mean the arrest of anyone still on the streets after a mandatory evacuation order goes out. Police and National Guardsman will patrol after the storm's arrival, and Gov. Bobby Jindal has said he requested additional search and rescue teams from other states.

Evacuation of coastal parishes was likely to start on Saturday, said Jindal. In St. Mary Parish, which hugs the coastline, the Louisiana Shrimp and Petroleum Festival — the state's oldest chartered harvest festival usually held over the Labor Day weekend has been canceled, officials said.

In New Orleans, city leaders and residents were taking Gustav's threat very seriously. Tulane, Xavier, Loyola universities and the University of New Orleans closed to allow students to evacuate or prepare for Gustav. Tulane officials unfurled newly created emergency plans and tested new communication systems, President Scott Cowen said.

Katrina caused $650 million in damages to the university. "I am absolutely sure that the city and state is much better prepared than they were before," Cowen said. "People themselves are also better prepared because they've gone through it."

Also, in 2005, Katrina veered at the last moment and headed to New Orleans, giving residents only a few days to prepare, councilman Arnie Fielkow said. This time, it's different. "From a city standpoint, we're significantly head of the game as far as planning," he said.

As city officials detailed evacuation plans, some residents weren't waiting to be told to leave.

Cars packed with clothes, boxes and pet carriers drove north among heavy traffic on Interstate 55, a major route out of the city. Gas stations around the city hummed. And nursing homes and hospitals began sending patients farther inland.

"I'm getting out of here. I can't take another hurricane," said Ramona Summers, 59, whose house flooded during Katrina. She hurried to help friends gather their belongings. Her car was already packed for Gonzales, nearly 60 miles away to the west of New Orleans.

Also Friday, President Bush declared a state of emergency in Louisiana, which authorizes the federal coordination of disaster-relief efforts and Vermillion Parish, La., issued a call for voluntary evacuation.

There are more than 5,000 temporary homes along the state's 70-mile coast, which was badly hit by Katrina three years ago. Officials are concerned because trailers are particularly vulnerable to being damaged in high winds.

In Jamaica, Gustav ripped off roofs, downed power lines and triggered landslides and flooding but no reported deaths. The death toll rose to 67 in Haiti and the Dominican Republic, where Gustav left dangerous floods.

In the Cayman Islands, two people were knocked down by huge waves as they tried to take pictures of the storm on Little Cayman, but there were no other immediate reports of injuries, said Hemant Balgobin, disaster manager for the Red Cross in the British territory.

There were reports of damaged homes in Cayman Brac and flooding throughout the islands but authorities had not yet fully assessed the situation, said Balgobin, who was on Grand Cayman, the largest in the chain.

"Things weren't really as bad as they could have been," he said.

The chances of New Orleans seeing winds of 39 mph or more within five days was between 50% and 60%, it said, warning that weather models "diverge tremendously over the northern Gulf" and that the most destructive winds could strike almost anywhere along the U.S. Gulf Coast.

Gustav was forcing shutdowns of many offshore oil operations, causing hikes in global crude prices. Wholesale gasoline prices also were shooting up in the Gulf region, forcing filling stations to raise pump prices ahead of Labor Day weekend.

The Gulf has 4,000 oil rigs and half of the USA's refining capacity. Hundreds of offshore workers have already been pulled out and analysts said the storm could send U.S. gas prices back over $4 a gallon.

New Orleans Mayor Ray Nagin said he would order a mandatory evacuation of the city if forecasters predict a Category-3 strike — or possibly even a Category 2 — within 72 hours. Homeland Security Secretary Michael Chertoff was in the region monitoring developments.

At least 78 people died in Haiti, Jamaica and the Dominican Republic from floods, mudslides and falling trees, including 25 around the city of Jacmel, Haiti, where Gustav first struck land Tuesday. Eight more people were buried when a cliff gave way in the Dominican Republic.

Meanwhile, another system, Tropical Storm Hanna, is slowly strengthening in the Caribbean.

As of 11 a.m., the 50-mph storm was located about 305 miles north of Grand Turk Island and was moving to the west at 8 mph, according to the National Hurricane Center.

Tropical storm watches have been issued for the southeastern Bahamas and the Turks and Caicos Islands. No direct affects from the storm on the USA can be forecast at this time, the center reports

Contributing: Douglas Stangllin in McLean, Va., Jim Bradshaw of The (Lafayette, La.) Daily Advertiser, the Associated Press and The Clarion-Ledger of Jackson, Miss.

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